What are the characteristics of ocean engineering? be badly in need of

Marine engineering refers to the new construction, reconstruction and expansion project with the aim of developing, utilizing, protecting and restoring marine resources, and the main part of the project is located on the seaward side of the coastline. Specifically, it includes: land reclamation, offshore dam project, artificial island, offshore and submarine material storage facilities, cross-sea bridge, submarine tunnel project, submarine pipeline, submarine electric (optical) cable project, exploration and development of marine mineral resources and its ancillary projects, offshore tidal power station, wave power station, thermoelectric power station and other marine energy development and utilization projects, large-scale marine farms, artificial fish reefs, salt pans, seawater desalination and other comprehensive utilization projects, and marine entertainment and sports.

It can be divided into three categories: coastal engineering, offshore engineering and deep sea engineering.

Coastal engineering

It has been highly valued since ancient times. It mainly includes coastal protection engineering, reclamation engineering, harbor engineering, estuary regulation engineering, marine dredging engineering, coastal fishery facilities engineering and environmental protection facilities engineering.

Offshore engineering

Also known as ocean engineering. It has developed rapidly since the middle of the 20th century. Mainly offshore platforms and artificial islands in shallow waters of continental shelf, as well as floating platforms, semi-submersible platforms, jack-up platforms, oil and gas exploration and production platforms, floating oil depots, floating refineries, floating airports and other construction projects in deep waters of continental shelf.

Deep sea engineering

Including unmanned submersibles and remote-controlled seabed mining facilities. Due to the complex changes of marine environment, marine engineering should not only consider the corrosion of seawater conditions and the pollution of marine life, but also bear the strong effects of typhoons, waves, tides, currents and ice, as well as the impact of beach evolution and sediment transport in shallow waters.

The application of marine basic science and related technical disciplines to marine development and utilization is a new comprehensive technical science, which also refers to various buildings or other engineering facilities and technical measures for the development and utilization of the ocean. The contents of marine development and utilization mainly include: marine resources development (biological resources, mineral resources, seawater resources, etc.). ), marine space utilization (coastal beach utilization, maritime transportation, maritime airports, offshore factories, submarine tunnels, submarine military bases, etc. ), ocean energy utilization (tidal power generation, wave power generation, temperature difference power generation, etc. ), coastal protection, etc. The term "marine engineering" was put forward in 1960s, and its content has been gradually developed and enriched with the exploitation of offshore oil, natural gas and other minerals in recent twenty or thirty years. According to the sea areas for marine development and utilization, marine engineering can be divided into coastal engineering, offshore engineering and deep-sea engineering, but there are overlaps among them. Ocean engineering begins with coastal engineering of coastal zone development. Countries along the Mediterranean Sea started sailing and built ports in BC 1000. As early as 306-200 BC, China built a port along the coast, and in the Eastern Han Dynasty (AD 25-220), it began to build coastal defense projects along the southeast coast. The Netherlands also began to build Haiti in the early Middle Ages, and then reclaimed land to compete with the sea for land. For a long time, with the development of navigation and the growth of production and construction needs, coastal engineering has been greatly developed, mainly including coastal protection engineering, reclamation engineering, harbor engineering, estuary regulation engineering, marine dredging engineering, coastal fishery engineering and environmental protection engineering. However, the term "coastal engineering" first appeared in the 1950s. With the formation and development of marine engineering hydrology, coastal dynamics and coastal dynamic geomorphology, coastal engineering has gradually formed a systematic technical discipline. Since the second half of the 20th century, the world population and economy have expanded rapidly, and the demand for protein and energy has also increased sharply. With the exploitation of oil and gas on the continental shelf and the continuous expansion of the scale of marine resources development and space utilization, the corresponding offshore engineering has become one of the fastest-growing projects in the past 30 years. Its main symbol is the emergence of offshore platforms for drilling and producing oil (gas), and its operation scope extends from the inshore waters with a water depth of 10 meter to the continental shelf waters with a water depth of 300 meters. Seabed mining has developed from nearshore shallow sea to deep sea. Now it is possible to drill oil in the sea area with water depth of1000m or more, drill in the ocean with water depth of 6000m or more, and collect manganese nodules at the seabed with water depth of 4000m. Marine diving technology has also developed rapidly, and it has been possible to carry out saturated diving. The diving depth of the loaded submersible can reach more than 10000 meters, and there are also marine robots for diving operations. In this way, offshore engineering in continental shelf waters and deep-sea engineering in deep-sea waters have gone far beyond the scope of coastal engineering, and the basic science and engineering technology applied have also gone beyond the scope of traditional coastal engineering, thus forming a new type of marine engineering. There are many types of structures in ocean engineering, such as gravity buildings, permeable buildings and floating structures. Gravity building is suitable for coastal zone and nearshore shallow water area, such as seawall, revetment, wharf, breakwater, artificial island, etc. , and made of soil, stone, concrete and other materials inclined, straight wall or mixed structure. Permeable buildings are suitable for shallow sea with soft soil foundation, and can also be used in waters with large water depth, such as piled wharves, island wharves and offshore platforms in shallow sea. Among them, offshore platforms are made of steel, reinforced concrete, etc. , can be fixed, can also be active. Floating structures are mainly suitable for deep-sea continental shelf waters, such as drilling ships, floating platforms and semi-submersible platforms, and can be used as oil and gas exploration and production platforms, floating oil storage tanks and refineries, floating power stations, floating airports and floating seawater desalination devices. In addition to the above three kinds, unmanned submersibles have been developed in recent 10 years for remote control of seabed mining production systems. The marine environment is complex and changeable, and marine engineering is often strongly influenced by typhoons (hurricanes), waves, tides, currents and ice. It is also influenced by complex topography, beach evolution and shallow water sediment transport. Marine environmental factors, such as temperature, earthquake, radiation, electromagnetism, corrosion and biological adhesion, also have an impact on some marine projects. Therefore, the stochastic characteristics of various dynamic factors need to be considered in the external force analysis of buildings and structures, the dynamic problems need to be considered in the structural calculation, the periodic load and the uncertainty of soil need to be considered in the foundation design, and the economy and durability need to be considered in the material selection. The cost of offshore engineering is huge, and the consequences of accidents are serious, so it is very important to strictly demonstrate and test its safety. The development and space utilization of marine resources and the construction of a large number of engineering facilities will bring various impacts on the marine environment, such as beach evolution, water pollution and deterioration of ecological balance. We must pay enough attention to it. In addition to forecasting, analysis and research, and strengthening on-site monitoring, various preventive and improvement measures should be taken.